Fluid dispensers having various types of dispensing valves for use with syringe barrel fluid supply reservoirs are generally well known in the field of fluid dispensing. The applications for the fluid dispensers vary widely, and, as such, so do the fluids held within the syringe barrels. These fluids may comprise single-component fluids or multi-component fluids, such as a fluid comprising composite materials. The composite materials may include any combination of fluid materials and/or particulate materials. The composite materials preferably have uniformly mixed concentrations rather than variable concentrations. A uniform concentration is preferable to variable concentrations because multi-component fluids are typically mixed to provide specific, consistent material properties in use. Unmixed fluids, on the other hand, have variable component concentrations that dispense from the fluid dispenser having variable material properties, which either create unacceptable variation in the final product or cause the fluid to be unusable for its intended purpose.
Multi-component fluids may include composite materials comprised of relatively heavily weighted particles suspended within a lightly weighted component fluid or multiple fluids having different densities. As such, these multi-component fluids tend to separate or settle over time due to the effects of gravity. This settling may occur before or even during the use of the syringe barrel with the fluid dispenser. For example, a syringe barrel may hold fluid silicone encapsulent fluid including fluorescent particulate material for use in the production of light emitting diodes (LEDs). The fluorescent material particulates are heavier than the fluid silicone encapsulent, which, due to the effects of gravity, cause the fluorescent material to settle out of the silicone encapsulent fluid. Thus, the resulting fluid/particulate mixture has an increasingly variable concentration over time. As the fluid/particulate mixture is dispensed, the particulate concentrations in the fluid mixture may vary with each application. As one example, this effect may create color variation in the light produced by the LEDs manufactured over that period of production.
Presently, manufacturers dispensing multi-component fluids prone to settling may actively distribute the components uniformly prior to installing the syringe barrel within the fluid dispenser. In this manner, the negative effects of component settling may be averted upon initial dispensing of the fluid from the fluid valve. This step adds time and cost to the dispensing process. Moreover, multi-component fluids, settling or separation of the separate components may still occur after initial dispensing. This creates a limited time period for dispensing fluid with a uniform concentration of components. In the event that the syringe barrel is not effectively emptied during that limited time period, the manufacturer must either dispose of the remaining fluid or remove the syringe barrel to once again actively distribute the remaining fluid to a uniform concentration.
There is a need for a fluid dispenser and method for dispensing a fluid having composite materials that addresses present challenges and characteristics such as those discussed above.